The present invention relates to a method and an apparatus for cleaning internal combustion engine crankcase blow-by gas and an internal combustion engine including said apparatus.
1. Field of the Invention
During the compression and power strokes in an internal combustion engine, the difference in gas pressures above and below a piston is sufficient to cause leakage (blow-by) of gas past the piston into the engine crankcase. The resulting increase in pressure within the crankcase can cause oil to pass by the engine oil seals and this pressure may also damage the seals.
To diminish the damaging effects of blow-by it is normal to relieve crankcase pressure by either venting the blow-by gas to atmosphere via an open breather or by connecting the crankcase to the engine intake air system whereby blow-by gas is conveyed to the air intake system and thence to the combustion chamber under the control of a pressure regulating valve. The pressure regulating valve maintains gas pressure within the crankcase between desirable limits. This latter arrangement constitutes a closed-circuit breather system.
The blow-by gas carries with it oil vapour and this exits the engine to atmosphere via the open breather or, in the closed-circuit breather system, is taken into the engine air inlet system and is partially or fully burned before exiting to atmosphere via the engine exhaust system. In either case, this results in undesirable emissions being emitted which contain either unburned oil or the products of burned oil. The oil content of the blow-by gas, where this is fed into the engine intake air system via a closed-circuit breather system, also leads to fouling of turbo-charger compressor vanes, engine poppet valves and other components in contact with inlet air.
2. Description of the Related Art
U.S. Pat. No. 3,533,385 and JP-A-61-171814 each disclose an apparatus for reducing the oil content of blow-by gas in an internal combustion engine, comprising: means for conveying blow-by gas away from the engine crankcase to a heat exchanger cooled by air from an engine air intake system, said blow-by gas being cooled by passing it through the heat exchanger; means for returning oil condensed from said cooled blow-by gas to the engine; and means for directing the cooled blow-by gas into the flow of engine inlet air, said means comprising a blow-by gas outlet.
In the case of U.S. Pat. No. 3,533,385, the blow-by gas outlet is located internally of the heat exchanger but is not adjacent to an air inlet end of the heat exchanger.
In the case of JP-A-61-171814, the blow-by gas outlet is external of the heat exchanger.